Wafer-level back-end fabrication systems and methods

ABSTRACT

Systems and methods may be provided for fabricating infrared focal plane arrays. The methods include providing a device wafer, applying a coating to the device wafer, mounting the device wafer to a first carrier wafer, thinning the device wafer while the device wafer is mounted to the first carrier wafer, releasing the device wafer from the first carrier wafer, singulating the device wafer into individual dies, each die having an infrared focal plane array, and hybridizing the individual dies to a read out integrated circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 62/233,056, filed Sep. 25, 2015 and entitled“WAFER-LEVEL BACK-END FABRICATION SYSTEMS AND METHODS,” which is herebyincorporated by reference in its entirety.

STATEMENT REGARDING GOVERNMENT SUPPORT

This invention was made with government support under FA8650-14-C-5508awarded by the United States Air Force. The government has certainrights in the invention.

TECHNICAL FIELD

One or more embodiments of the invention relate generally to infraredcameras and, more particularly, to manufacturing focal plane arrays atthe wafer-level.

BACKGROUND

Dies, such as focal plane arrays, are typically produced collectively inarrays on wafer substrates. Back-end or back-end of line fabrication offocal plane arrays is often performed serially after front-endwafer-level detector processing. Entire wafers are generally front-endprocessed and singulated, and then back-end processing is performed at adie-level. Back-end processing can include processes such as thinning,polishing, coating, and hybridizing. Typically, thinning, polishing,coating, and hybridizing processes are performed after singulating thewafer into individual dies. Thus, if there are ten arrays on a wafer,the thinning process is performed ten different times, resulting in atime-consuming and expensive processing technique. As a result, asignificant portion of focal plane array cost is attributed to thetraditional approach of back-end of line fabrication. The traditionalapproach of wafer-level processing without a carrier has been tried, buthas been typically abandoned because of damage that occurs to thebackside optical surface during backside processing.

As a result, there is a need for improved techniques for fabricatingfocal plane arrays for imaging devices such as Group III-V and II-IVcompound semiconductors for infrared cameras.

SUMMARY

The present disclosure describes systems and methods that perform themajority of back-end of line manufacturing steps of infrared focal planearrays at the wafer-level, rather than at the die-level. Such steps mayinclude all steps prior to a hybridization step, and may includepolishing, substrate removal, and coating. These steps are performed ona plurality of dies at the same time, rather than on one die at a time.Thus, the back-end of line process is simplified, and the time and costof the back-end of line process is reduced. That is, after the front-endprocesses on a detector wafer's surface have been completed, theback-end process may be directly performed on the entire wafer, and thenthe wafer can be singulated to form a plurality of focal plane arrays.

According to an embodiment, a method is disclosed for fabricating aninfrared focal plane array. The method includes providing a devicewafer, applying a coating to the device wafer, mounting the device waferto a first carrier wafer, thinning the device wafer while the devicewafer is mounted to the first carrier wafer, releasing the device waferfrom the first carrier wafer, singulating the device wafer intoindividual dies, each die having an infrared focal plane array, andhybridizing the individual dies to a read out integrated circuit.

According to another embodiment, a method is disclosed for fabricatingan infrared focal plane array. The method includes providing a detectorwafer comprising a substrate and a detector layer, applying a firstprotective coating over the detector layer, thinning the substrate whilethe first protective coating is over the detector layer, and applying anantireflective coating over the thinned substrate while the firstprotective coating is over the detector layer. The first protectivecoating mechanically supports the detector wafer.

According to another embodiment, a method is disclosed for fabricatingan infrared focal plane array. The method includes providing a wafercomprising a substrate and an antireflective coating, mounting the waferto a carrier wafer, thinning the substrate, and forming one or moredetector layers over the substrate. The thinning and the forming areperformed at a wafer level.

The scope of the invention is defined by the claims, which areincorporated into this Summary by reference. A more completeunderstanding of embodiments of the invention will be afforded to thoseskilled in the art, as well as a realization of additional advantagesthereof, by a consideration of the following detailed description of oneor more embodiments. Reference will be made to the appended sheets ofdrawings that will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram illustrating a system for capturing imagesin accordance with an embodiment.

FIG. 2 shows a perspective view illustrating a focal plane arrayfabricated in accordance with an embodiment.

FIG. 3 shows one flow diagram illustrating a method of fabricating afocal plane array in accordance with an embodiment.

FIGS. 4A-4G show cross-sectional side views of a wafer subjected to themethod illustrated in FIG. 3.

FIG. 5 shows a second flow diagram illustrating a method of fabricatinga focal plane array in accordance with an embodiment.

FIGS. 6A-6L show cross-sectional side views of a wafer subjected to themethod illustrated in FIG. 5.

FIG. 7 shows a third flow diagram illustrating a method of fabricating afocal plane array in accordance with an embodiment.

FIGS. 8A-8I show cross-sectional side views of a wafer subjected to themethod illustrated in FIG. 7.

FIG. 9 illustrates a block diagram of a system for fabricating a focalplane array in accordance with an embodiment.

Embodiments of the invention and their advantages are best understood byreferring to the detailed description that follows. It should beappreciated that like reference numerals are used to identify likeelements illustrated in one or more of the figures.

DETAILED DESCRIPTION

Systems and methods are disclosed herein to provide enhanced fabricationof infrared focal plane arrays. The majority of the back-end fabricationsteps are performed at the wafer-level, which extends the die-levelfabrication of the focal plane arrays as close as possible to the end ofthe manufacturing process. Such steps performed at the wafer levelinclude polishing, substrate removal, application of an antireflectivecoating, and application of a protective coating. The processesdescribed herein may be applied to any Group III-IV and II-VI compoundsemiconductors such as indium antimonide (InSb) and indium galliumarsenide (InGaAs), superlattices (SLS), quantum well infraredphotodetectors (QWIPs), and mercury cadmium telluride.

In various embodiments, carrier wafers are used to mechanically supportthinned detector wafers, and serve as a protective mechanical barrier toscratching of the antireflective coating, which in some embodiments isdeposited prior to carrier mounting. At a later step, the carrier wafercan be released to eliminate any unwanted absorption in the light pathof the final focal plane array assembly. Otherwise, if the carrier waferremains intact, an infrared (IR) transparent carrier within the wavebandof interest can be utilized to minimize absorption effects.

Referring now to FIG. 1, a block diagram is shown illustrating a system100 (e.g., an infrared camera) for capturing and processing images inaccordance with one or more embodiments. System 100 may include, in oneimplementation, a processing component 110, a memory component 120, animage capture component 130, a control component 140, and a displaycomponent 150. Optionally, system 100 may include a sensing component160.

System 100 may represent for example an infrared imaging device, such asan infrared camera, to capture and process images, such as video imagesof a scene 170. The system 100 may represent any type of infrared cameraadapted to detect infrared radiation and provide representative data andinformation (e.g., infrared image data of a scene) or may represent moregenerally any type of electro-optical sensor system. System 100 maycomprise a portable device and may be incorporated, e.g., into a vehicle(e.g., an automobile or other type of land-based vehicle, an aircraft, amarine craft, or a spacecraft) or a non-mobile installation requiringinfrared images to be stored and/or displayed or may comprise adistributed networked system.

In various embodiments, processing component 110 may comprise any typeof a processor or a logic device (e.g., a programmable logic device(PLD) configured to perform processing functions). Processing component110 may be adapted to interface and communicate with components 120,130, 140, and 150 to perform method and processing steps and/oroperations, as described herein such as controlling biasing and otherfunctions (e.g., values for elements such as variable resistors andcurrent sources, switch settings for timing such as for switchedcapacitor filters, ramp voltage values, etc., depending on the type ofapplications and image capture component) along with conventional systemprocessing functions as would be understood by one skilled in the art.

Memory component 120 comprises, in one embodiment, one or more memorydevices adapted to store data and information, including for exampleinfrared data and information. Memory device 120 may comprise one ormore various types of memory devices including volatile and non-volatilememory devices. Processing component 110 may be adapted to executesoftware stored in memory component 120 so as to perform method andprocess steps and/or operations described herein.

Image capture component 130 comprises, in one embodiment, any type ofimage sensor, such as for example one or more infrared sensors (e.g.,any type of multi-pixel infrared detector, such as a focal plane arraywith a photovoltaic detector or other types of infrared detectors) forcapturing infrared image data (e.g., still image data and/or video data)representative of an image, such as scene 170. In some embodiments, thefocal plane array is manufactured according to the methods describedherein. In one implementation, the infrared sensors of image capturecomponent 130 provide for representing (e.g., converting) the capturedimage data as digital data (e.g., via an analog-to-digital converterincluded as part of the infrared sensor or separate from the infraredsensor as part of system 100). In one aspect, the infrared image data(e.g., infrared video data) may include non-uniform data (e.g., realimage data) of an image, such as scene 170. Processing component 110 maybe adapted to process the infrared image data (e.g., to provideprocessed image data), store the infrared image data in memory component120, and/or retrieve stored infrared image data from memory component120. For example, processing component 110 may be adapted to processinfrared image data stored in memory component 120 to provide processedimage data and information (e.g., captured and/or processed infraredimage data).

Control component 140 may include, in one embodiment, a user inputand/or interface device, such as a rotatable knob (e.g., potentiometer),push buttons, slide bar, keyboard, etc., that is adapted to generate auser input control signal. Processing component 110 may be adapted tosense control input signals from a user via control component 140 andrespond to any sensed control input signals received therefrom.Processing component 110 may be adapted to interpret such a controlinput signal as a parameter value, as generally understood by oneskilled in the art.

In one embodiment, control component 140 may include a control unit(e.g., a wired or wireless handheld control unit) having push buttonsadapted to interface with a user and receive user input control values.In one implementation, the push buttons of the control unit may be usedto control various functions of the system 100, such as autofocus, menuenable and selection, field of view, brightness, contrast, noisefiltering, high pass filtering, low pass filtering, and/or various otherfeatures as understood by one skilled in the art.

Display component 150 may include, in one embodiment, an image displaydevice (e.g., a liquid crystal display (LCD) or various other types ofgenerally known video displays or monitors). Processing component 110may be adapted to display image data and information on the displaycomponent 150. Processing component 110 may be adapted to retrieve imagedata and information from memory component 120 and display any retrievedimage data and information on display component 150. Display component150 may include display electronics, which may be utilized by processingcomponent 110 to display image data and information (e.g., infraredimages). Display component 150 may be adapted to receive image data andinformation directly from image capture component 130 via the processingcomponent 110, or the image data and information may be transferred frommemory component 120 via processing component 110.

Optional sensing component 160 may include, in one embodiment, one ormore sensors of various types, depending on the application orimplementation requirements, as would be understood by one skilled inthe art. The sensors of optional sensing component 160 provide dataand/or information to at least processing component 110. In one aspect,processing component 110 may be adapted to communicate with sensingcomponent 160 (e.g., by receiving sensor information from sensingcomponent 160) and with image capture component 130 (e.g., by receivingdata and information from image capture component 130 and providingand/or receiving command, control, and/or other information to and/orfrom one or more other components of system 100).

In various implementations, sensing component 160 may provideinformation regarding environmental conditions, such as outsidetemperature, lighting conditions (e.g., day, night, dusk, and/or dawn),humidity level, specific weather conditions (e.g., sun, rain, and/orsnow), distance (e.g., laser rangefinder), and/or whether a tunnel orother type of enclosure has been entered or exited. Sensing component160 may represent conventional sensors as generally known by one skilledin the art for monitoring various conditions (e.g., environmentalconditions) that may have an effect (e.g., on the image appearance) onthe data provided by image capture component 130.

In some implementations, optional sensing component 160 (e.g., one ormore of sensors) may include devices that relay information toprocessing component 110 via wired and/or wireless communication. Forexample, optional sensing component 160 may be adapted to receiveinformation from a satellite, through a local broadcast (e.g., radiofrequency (RF)) transmission, through a mobile or cellular networkand/or through information beacons in an infrastructure (e.g., atransportation or highway information beacon infrastructure), or variousother wired and/or wireless techniques.

In various embodiments, components of system 100 may be combined and/orimplemented or not, as desired or depending on the application orrequirements, with system 100 representing various functional blocks ofa related system. In one example, processing component 110 may becombined with memory component 120, image capture component 130, displaycomponent 150, and/or optional sensing component 160. In anotherexample, processing component 110 may be combined with image capturecomponent 130 with only certain functions of processing component 110performed by circuitry (e.g., a processor, a microprocessor, a logicdevice, a microcontroller, etc.) within image capture component 130.Furthermore, various components of system 100 may be remote from eachother (e.g., image capture component 130 may comprise a remote sensorwith processing component 110, etc. representing a computer that may ormay not be in communication with image capture component 130).

FIG. 2 shows a perspective view illustrating an infrared detector device200 having an array 202 of infrared detector elements 204 that may beused to capture image data such as infrared image data for, for example,image capture component 130 of FIG. 1. The array 202 may have any numberof infrared detector elements 204, and the infrared detector elements204 may be any type of detector, including for example, thermocouples,thermopiles, pyroelectric detectors, and photovoltaic detectors. Thedetector elements 204 may be coupled to associated readout circuitry asdiscussed further herein.

In one suitable configuration that is sometimes discussed herein as anexample, device 200 may be a focal plane array that may be implementedin, for example, image capture component 130 of FIG. 1. Each detectorelement 204 may be formed from one or more layers of material such asone or more absorber layers, one or more passivation layers, one or moretemperature sensitive resistive layers, one or more cap layers, one ormore overglass layers, one or more antireflective layers, and/or otherlayers or elements.

In a focal plane array configuration, ROIC 210 may include a ROICsubstrate formed from silicon or germanium (as examples). Detectorelements 204 may be arranged to convert incident light such as infraredlight 201 into, for example, detectable electrical signals based onchanges in electrical properties of the detector element when the light201 is incident. Each infrared detector element 204 may be coupled to aROIC for processing and reading out the electrical signals, as would beunderstood by one skilled in the art.

ROIC may incorporate circuitry that is placed in spatial proximity tothe detector elements 204 to perform the functions of detector interfaceand multiplexing. The ROIC circuitry associated with detector elements204 may, for example, be located in a separate substrate and may includean array of unit cells, column amplifiers, a column multiplexer, and arow multiplexer integrated on to a single ROIC silicon die, or othertype of circuitry depending on the type of detector and particularapplication. Each detector element 204 in the array 202 may communicatewith the ROIC.

Referring to FIG. 3 and FIGS. 4A-4G, a method 300 for fabricating afocal plane array is described. At step 302 and FIG. 4A, a device wafer405 is provided. The device wafer 405 may or may not be front-sideprocessed. In embodiments where the wafer 405 has been front-sideprocessed, a wafer measuring 3 inches across may include 30 detectordies, and a wafer measuring 4 inches across may include 60 detectordies.

At step 302 and FIG. 4B, a coating 410 is applied to the device wafer.In one embodiment, the coating 410 is a protective coating, and anadhesive tape or a spin-on photoresist is applied to the active orpatterned surface of the wafer to protect the circuitry. For example,photoresist material is applied and then cured to form the protectivecoating 410.

In another embodiment, the coating 410 is an antireflective coating. Thecomposition of the antireflective coating depends on the wavelength thatshould be reflected. The antireflective coating may be a single layer orconsist of multiple layers. For example, the antireflective coating mayinclude a series or stack of dielectric antireflection coatings havingthe desired properties.

At step 306 and FIG. 4C, the device wafer 405 is bound or mounted to acarrier wafer 415. The carrier wafer 415 provides mechanical support tothe device wafer 405 as the device wafer 405 is sent through the variousprocessing steps. A polymeric adhesive (e.g., epoxy) may be used to bondthe device wafer 405 to the carrier wafer 415. The polymeric adhesivesused for temporary wafer bonding are typically applied by spin coatingor spray coating from solution or laminating as dry-film tapes. Thepolymeric adhesives should exhibit high bonding strength to the devicewafer 405 and the carrier wafer 415.

Common carrier materials include silicon (e.g., a blank device wafer),soda lime glass, borosilicate glass, sapphire, and various metals andceramics. The carrier material is, in several embodiments, inexpensiveand closely matches the thermal expansion properties of the detector andsubstrate material of the device wafer. The carriers may be square,rectangular, or round but are typically sized to match the device waferso that the bonded assembly can be handled in conventional processingtools and cassettes.

At step 308 and FIG. 4D, the backside or inactive side of the devicewafer 405 is ground, thinned, and/or polished until the device wafer 405reaches a desired thickness. The device wafer 405 may be thinned bymechanical and/or chemical polishing or any other technique. A varietyof wafer thinning techniques have been proposed and used, ranging frommachines providing simple mechanical abrasion using, e.g., an abrasivegrinding wheel, to chemical etching and polishing techniques, back sidegrinder, and combinations of these, e.g. chemical mechanical polishing(CMP).

At step 310 and FIG. 4E, the device wafer 405 is released from thecarrier wafer 415. Once the processing steps are performed, a mechanicaldevice may be used to debond and/or demount the device wafer 405 fromthe carrier wafer 415. Thermal, thermomechanical, or chemical processesmay also be used to remove or debond the device wafer 405 from thecarrier wafer 415.

In some embodiments, the carrier wafer 415 and device wafer 405 are notseparated. In these cases, the carrier wafer 415 is a transparentcarrier within the waveband of interest that minimizes absorptioneffects. The transparent carrier is transparent to radiation in thedesired wavelength, such as wavelengths in the infrared or near-infraredspectrum. In various embodiments, the transparent carrier is made of amaterial that is substantially transparent to radiation in the infraredspectral range, such as float zone silicon.

At step 312 and FIG. 4F, the device wafer 405 is singulated intoindividual dies. After the processing steps are completed, the wafersare singulated, separating the die from the wafer. This “dicing,”separation or singulating operation is commonly carried out by sawingthrough the “streets” between the dies within the wafers.

At step 314 and FIG. 4G, the individual dies are hybridized or bonded toa ROIC 420. The hybridization process includes permanently mechanicallyand electrically bonding the detector of the device wafer 405 and theROIC 420 through use of metallic bonds between conductive contacts ofthe detector and conductive contacts of the ROIC 420. In one embodiment,the die may be bump-bonded to the ROIC 420 using bonding bumps, atechnique well known to those skilled in the art.

Referring now to FIG. 5 and FIGS. 6A-6L, a detailed method 500 forfabricating a focal plane array is described. At step 502 and FIG. 6A, adetector wafer 605 including substrate 605 a and a detector layer 605 bor detector components is provided. The detector layer 605 b includes aplurality of interconnects 608. In various embodiments, theinterconnects 608 are formed from one or more metals. In thisembodiment, the substrate 605 a is front-side processed to include theactive circuitry and components of the focal plane array.

At step 504 and FIG. 6B, a first protective coating 610 is applied overthe detector layer 605 b and the interconnects 608. As explained above,a protective coating acts to protect the active components of thedetector wafer during processing.

At step 506 and FIG. 6C, the front side or active side of the detectorwafer 605 is bonded to a first carrier wafer 615. In some embodiments,the first carrier wafer 615 is not needed because the first protectivecoating 610 is robust enough to mechanically support the detector wafer605. For example, the first protective coating 610 may include a spin-onglass or an abrasion resistant layer at a thickness that providessufficient strength and support to the detector wafer 605.

At step 508 and FIG. 6D, the backside or inactive side of the substrate605 a of the detector wafer 605 is thinned.

At step 510 and FIG. 6E, an antireflective coating 620 is applied overthe backside of the thinned substrate 605 a.

At step 512 and FIG. 6F, the detector wafer 605 is released from thefirst carrier wafer 615.

At step 514 and FIG. 6G, a second protective coating 625 is applied overthe antireflective coating 620 and the backside of the detector wafer605 is bonded to a second carrier wafer 630. The second carrier wafer630 may not be needed in cases where the second protective coating 625and/or the first protective coating 610 are strong enough tomechanically support the detector wafer 605.

At step 516 and FIG. 6H, the detector wafer 605 and second carrier wafer630 are singulated into individual dies 640.

At step 518 and FIG. 6I, the first protective coating 610 is removedfrom the dies 640 using methods known in the art. For example, the firstprotective coating may be removed by wet stripping or oxygen plasmaashing.

At step 520 and FIG. 6J, the individual dies 640 are hybridized to aROIC 635. For example, the interconnects 608 may be connected toconductive contacts of the ROIC 635.

At step 522 and FIG. 6K, the gaps between the detector layer 605 b andthe ROIC 635 is back-filled with a thermally conductive material 645,for example, an epoxy. This step is not needed in all cases, but may beused to reinforce the interconnects 608.

At step 524 and FIG. 6L, the individual dies 640 are released from thesecond carrier wafer 630 and the second protective coating 625 isremoved.

Referring now to FIG. 7 and FIGS. 8A-8I, another detailed method 700 forfabricating a focal plane array is described. At step 702 and FIG. 8A, asubstrate 805 is provided.

At step 704 and FIG. 8B, an antireflective coating 810 is applied overthe substrate 805.

At step 706 and FIG. 8C, the substrate 805 is bonded to a carrier wafer815.

At step 708 and FIG. 8D, the substrate 805 is thinned.

At step 710 and FIG. 8E, a detector layer 820 or detector components isformed over the substrate to form a detector wafer 835. The detectorlayer 820 includes a plurality of interconnects 828.

At step 712 and FIG. 8F, the detector wafer 835 and carrier wafer 815are singulated into individual dies 840.

At step 714 and FIG. 8G, the individual dies 840 are hybridized to aROIC 845.

At step 716 and FIG. 8H, the gap between the detector layer 820 and theROIC 845 is back-filled with a thermally conductive material 850, forexample an epoxy. This step is not required in all cases.

At step 718 and FIG. 8I, the detector wafer 835 is released from thecarrier wafer 815.

As would be understood by one skilled in the art, at various stagesduring the processes of FIGS. 3, 5, and 7, other layers such aspassivation layers, photoresist layers, additional sacrificial layers,antireflection layers, and/or other suitable layers may be deposited,patterned and/or removed in whole or in part to form, for example, thestructures of FIGS. 4G, 6L, and 8I.

FIG. 9 illustrates a system 900 that may be used to fabricate a focalplane array in accordance with one or more embodiments. System 900includes front-end processing system 905 and a back-end processingsystem 910. Front-end processing system 905 performs various front-endprocessing steps such as forming the detector layer and interconnects.Back-end processing system 910 performs various back-end processingsteps such as thinning, polishing, coating, hybridizing, and singulatingwafers.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A method of fabricating an infrared focal planearray, comprising: providing a device wafer; applying a coating to thedevice wafer; mounting the device wafer to a first carrier wafer;thinning the device wafer while the device wafer is mounted to the firstcarrier wafer; releasing the device wafer from the first carrier wafer;singulating the device wafer into individual dies, each die having aninfrared focal plane array; and hybridizing the individual dies to aread out integrated circuit.
 2. The method of claim 1, wherein: thecoating comprises at least one of a protective coating or anantireflective coating; and the device wafer comprises a substrate on abackside of the device wafer and a detector layer on a frontside of thedevice wafer.
 3. The method of claim 2, further comprising: mounting asecond carrier wafer to the backside of the device wafer beforesingulating the device wafer into individual dies.
 4. The method ofclaim 3, further comprising releasing the second carrier wafer afterhybridizing the individual dies.
 5. The method of claim 3, wherein thesecond carrier wafer is substantially transparent to infrared radiation,and further comprising retaining the second carrier wafer afterhybridizing the individual dies.
 6. The method of claim 1, furthercomprising forming one or more detector layers on a frontside of thedevice wafer while the first carrier wafer is mounted; and wherein thedevice wafer comprises a substrate and an antireflective coating.
 7. Themethod of claim 1, wherein releasing the device wafer from the firstcarrier occurs after hybridizing the individual dies; and wherein thefirst carrier wafer is substantially transparent to infrared radiation,and further comprising retaining the first carrier wafer afterhybridizing the individual dies.
 8. An infrared imaging device,comprising: an infrared focal plane array fabricated according to themethod of claim
 1. 9. A system for performing the method of claim 1comprising: a front-end processing system; and a back-end processingsystem.
 10. A method of fabricating an infrared focal plane array,comprising: providing a detector wafer comprising a substrate and adetector layer; applying a first protective coating over the detectorlayer, wherein the first protective coating mechanically supports thedetector wafer; thinning the substrate while the first protectivecoating is over the detector layer; and applying an antireflectivecoating over the thinned substrate while the first protective coating isover the detector layer.
 11. The method of claim 10, further comprisingapplying a second protective coating over the antireflective coating,wherein the second protective coating mechanically supports the detectorwafer.
 12. The method of claim 11, further comprising: singulating thedetector wafer into individual dies; removing the first protectivecoating; hybridizing the individual dies to a read out integratedcircuit; and removing the second protective coating.
 13. An infraredimaging device, comprising: an infrared focal plane array fabricatedaccording to the method of claim
 10. 14. A system for performing themethod of claim 10 comprising: a front-end processing system; and aback-end processing system.
 15. A method of fabricating an infraredfocal plane array, comprising: providing a wafer comprising a substrateand an antireflective coating; mounting the wafer to a carrier wafer;thinning the substrate; and forming one or more detector layers over thesubstrate. wherein the thinning and the forming are performed at a waferlevel.
 16. The method of claim 15, further comprising singulating thewafer into individual dies after forming the one or more detectorlayers.
 17. The method of claim 16, further comprising hybridizing theindividual dies to a read out integrated circuit.
 18. The method ofclaim 17, further comprising releasing the carrier wafer afterhybridizing the individual dies to a read out integrated circuit.
 19. Aninfrared imaging device, comprising: an infrared focal plane arrayfabricated according to the method of claim
 15. 20. A system forperforming the method of claim 15 comprising: a front-end processingsystem; and a back-end processing system.